1. Field of the Invention
The present invention relates to a technique for driving data lines used in control of unit circuits, such as pixel circuits of a display device.
2. Description of the Related Art
In recent years, electro-optical devices using organic EL elements (organic electroluminescent elements) have been under development. Organic EL elements emit light themselves, and do not require back lighting. Accordingly, it is expected that such elements will make it possible to achieve display devices that have a lower power consumption, high visual field angle and high contrast ratio. Furthermore, in the present specification, the term “electro-optical device” refers to a device that converts an electrical signal into light. A typical example of an electro-optical device is a device that converts an electrical signal expressing an image into light representing an image; such a device is especially suitable as a display device.
FIG. 1 is a block diagram which illustrates the general structure of a display device using organic EL elements. This display device has a display matrix section 120, a gate driver 130, and a data line driver 140. The display matrix section 120 has a plurality of pixel circuits 110 that are arranged in the form of a matrix, and an organic EL element 114 is disposed in each pixel circuit 110. A plurality of data lines X1, X2 . . . that extend along the column direction of the matrix, and a plurality of gate lines Y1, Y2 . . . that extend along the row direction of the matrix, are respectively connected to the matrix of the pixel circuits 110.
In cases where a large display panel is constructed using the configuration shown in FIG. 1, the electrostatic capacitance Cd of each data line is fairly large. When the electrostatic capacitance Cd of the data lines is large, considerable time is required to drive the data lines. It has been very difficult to construct a large display panel using organic EL elements because the large number of organic EL elements require very high driving speed.
The above mentioned problem is not limited to display devices using organic EL elements, but is also common to display devices and electro-optical devices using current-driven light-emitting elements other than organic EL elements. Furthermore, this problem is not limited to light-emitting elements, but is also common to general electronic devices using current-driven elements that are driven by an electric current.